Cascade Cyclizations Triggered by Photochemically Generated Carbamoyl Radicals Derived from Alkyl Amines

Abstract

We report on a visible light-mediated cascade carbamoylation/cyclization of acrylamides using dihydropyridyl carbamoyl donors derived from alkyl amines. Diversely selected acrylamides including 2-cyano-N-arylacrylamides, indolyl-and benzimidazolyl acrylamides, and 2-alkynyl-N-aryl acrylamides participate in this reaction, providing products in good yields. The highlights of this photochemical method include the application of alkyl amine-derived carbamoyl donors, peroxide-free reaction conditions, and a broad scope.

Photoinduced Direct Carbamoylation of Ethers with Isocyanates towards synthesis of α- Amide Substituted Ether Derivatives

“…9 10 11 12 The main approaches for amides synthesis based on C(sp 3 )–H functionalization could be summarized as follows (Scheme 1 A): a) amidation of alkanes using benzamides; 13 14 15 16 17 b) aminocarbonylation using CO as carbonyl source; 18 19 20 21 22 23 24 c) carbamoylation using specific amide source. 25 26 27 28 29 30 However, there are still many drawbacks in these methods to overcome, such as high temperatures, the use of ligand or toxic gas CO, which are neither eco-friendly nor beneficial to the occupational safety and health. Moreover, some important drugs require direct C(sp 3 )–H carbamoylation, revealing the significance of developing amide sources.…”

Metal-free synthesis of carbamoylated dihydroquinolinones via cascade radical annulation of cinnamamides with oxamic acids

“…The decarboxylative radical cascade cyclization strategy has been used extensively for the efficient synthesis of N-heterocycles. 9 Although functionalized dihydroquinolinones have been synthesized by various methods including Friedel–Crafts cyclization, 10 transition metal-catalyzed reactions 11 and radical reactions, 12 surprisingly, the carbamoylated dihydroquinolinone synthesis has not been explored, except for a single example of the silver-catalyzed carbamoyl radical addition/cyclization of cinnamamide with 71% yield reported by Mai and co-workers 13 as part of the acyl radical cascade cyclization study (Scheme 1a) and a single example reported by Singh and co-workers 14 of photochemical carbamoylation of 2-alkynyl- N -aryl acrylamide with 76% yield using 10 mol% of Cu(OTf) 2 and a photocatalyst (Scheme 1b). Very recently, Zhou and co-workers 15 disclosed the carbamoylation of N -arylcinnamamides with 4-carbamoyl-Hantzsch ester (Scheme 1c).…”

Persulfate-Promoted Carbamoylation/Cyclization of Alkenes: Synthesis of Amide-Containing Quinazolinones

“…Li and co-workers developed a convenient and practical method for carbamoylated benzimidazo [2,1-a]isoquinolin-6(5 H )-ones from 2-arylbenzoimidazoles and oxamic acids [ 62 ]. Very recently, Anand Singh et al developed a visible-light-induced cascade carbamoylation/cyclization of acrylamides with 4-carbamoyl-1,4-dihydropyridines as carbamoylation reagents [ 63 ]. However, to our knowledge, the carbamoyl-radical-triggered cascade cyclization reaction of N3-alkenyl-tethered quinazolinones to afford amide-containing quinazolinones has never been reported.…”